Fleet General Nielssen serves as the Commandant of the Officer Candidate School on Sanctuary, having taken a temporary pay cut and rank assignment of colonel to qualify. Because of this he exemplifies the ideal soldier—one who’s so dedicated to military service that he skips a comfortable and honorable retirement to continue to play an active role in the military long after he’s disqualified for combat roles. A disabled combat veteran, he spends most of his time in a wheelchair, although he’s able to stand and walk for brief periods like parade and inspection. He worries about the safety and success of his cadets, and he dispenses a great deal of advice when giving them their temporary commissions and sending them on their training missions. He respects Johnnie enough to trust that he’ll be able to break the string of bad luck that’s plagued the temporary commission pips that he himself broke in on his apprenticeship cruise many years prior.